Larson Davis SoundTrack LxT, User Manual

Page: 106 / 307

LxT Manual Calibration Without Preamplifier
7-13
When a calibration has been performed using any of the four
preamplifiers listed above, that calibration information is
saved for that preamplifier. If the preamplifier is switched
from one of these types to another, then the calibration
information already saved for that new preamplifier type is
recalled. As long as the same microphone is being used with
that preamplifier, the calibration should be correct.
Direct Data Input
Self-noise values can also be entered manually when using
preamplifiers and/or microphones not included in the LxT
data base. See also ‘Direct Data Input” on page 7-13.
Overload Level
The overload level is the highest peak level which can be
measured without overloading the input of the LxT.
Under Range Level
The Under Range Level is the higher of the following:
(1) Noise Floor plus 10 dB
(2) Actual point where the log-linearity exceeds maximum
permitted value
Except for very low noise level microphones, the under
range level is usually determined by (1).
Calibration Without Preamplifier
There may be situations where the microphone preamplifier
provided with the LxT is not being used. For example when
a hydrophone is being used, no level calibrator is available
so the sensitivity must be input directly by the user. When
the preamplifier has been disconnected, the
Sensitivity tab
appears as shown in FIGURE 7-9.